N-Alkyl-substituted polyamides and copolyamides having long methylene chain units

N-Alkyl-substituted polyamides and copolyamides have been prepared from N,N′-dialkyl p-xylenediamine and N,N′-dialkyl hexamethylenediamine with long-chain aliphatic dicarboxylic acids. Crystalline N-alkyl polyamides were obtained by the use of dicarboxylic acids higher than C₁₆. The melting point versus composition curves for the crystalline N-alkyl copolyamides which were prepared from a mixture of diamine and the corresponding N-alkyl diamine with α,ω-octadecanedioic acid showed convex type plots. X-ray examination of N-alkyl copolyamides revealed that all the systems behaved in the same basic manner, the second component was always present without dissolving in the lattice of the first. Dilatometric curves showed two inflection points, corresponding to the melting points of the N-alkyl and unsubstituted polyamides respectively. From these results, a block copolymer structure was suggested for the N-alkyl copolyamides. The mechanisms for the formation of the block structure were also discussed.     

Unprecedented Diastereoselective Arylogous Michael Addition of Unactivated Phthalides

The first highly enantioselective arylogous Michael reaction (AMR) of 3-unsubstituted phthalides has been described. This phase-transfer methodology, which uses catalytic amounts of KOH/18-crown-6 catalyst in mesitylene in the presence of N,O-bis(trimethylsilyl)acetamide (BSA), gives access to a broad range of 3-monosubstituted phthalides with high levels of syn diastereoselectivity and good yields, starting from 3-unsubstituted derivatives and diverse α,β-unsaturated carbonyl compounds. The reaction also applies to unactivated 3-alkyl phthalides to afford 3,3-dialkyl derivatives. A plausible mechanism has been suggested. DFT analysis of possible transition states gives a rationale of the high syn diastereoselectivity observed and its correlation with the solvent's dielectric constant.     

Lipophilic ternary complexes in liquid–liquid extraction of trivalent lanthanides

The formation of ternary complexes between lanthanide ions [Nd(III) or Eu(III)], octyl(phenyl)-N,N-diisobutyl-carbamoylmethylphosphine oxide (CMPO), and bis-(2-ethylhexyl)phosphoric acid (HDEHP) was probed by liquid–liquid extraction and spectroscopic techniques. Equilibrium modeling of data for the extraction of Nd(III) or Eu(III) from lactic acid media into n-dodecane solutions of CMPO and HDEHP indicates the predominant extracted species are of the type [Ln(AHA)₂(A)] and [Ln(CMPO)(AHA)₂(A)], where Ln?=?Nd or Eu and A represents the DEHP^? anion. FTIR (for both Eu and Nd) and visible spectrophotometry (in the case of Nd) indicate the formation of the [Ln(CMPO)(A)₃] complexes when CMPO is added to n-dodecane solutions of the LnA₃ compounds. Both techniques indicate a stronger propensity of CMPO to complex Nd(III) versus Eu(III).     

1,2-Fused pyrimidines. III. Derivatives of 12H-pyrido[1′,2′:1,2]pyrimido[4,5-b]quinoline,a novel heterocyclic system

Reactivities of 2-amino-4H-pyrido[1,2-a]pyrimidin-4-ones and 4-amino-2H-pyrido[1,2-a]pyrimidin-2-ones, both N,N-dialkyl and (N-alkyl, N-phenyl)substituted, when treated with the N,N-dimethylformamide/phosphorus oxychloride Vilsmeier-Haack reagent XII were compared. Starting from 2-[(N-alkyl, N-phenyl)amino] compounds IXa,b , the expected XVIa,b and XVIIa,b were obtained, which are derivatives of 12H-pyrido[1′,2′:1,2]pyrimido[4,5-b]quinoline, a novel heterocyclic system. When 2-(phenylamino) compound IXc was used a mixture of 3-formylderivative XVIII and 12H-pyrido-[1′,2′:1,2]pyrimido[4,5-b]quinolin-12-one ( XIX ) resulted from the reaction. On the other hand, 2-(dialkylamino)-4H-pyrido[1,2-a]pyrimidin-4-ones IIIa-c plainly afforded high yields of 3-formylderivatives XIVa-c. In contrast, no significant reaction occurred when 4-(dialkylamino) and 4-[(N-alkyl,N-phenyl)amino] compounds IIa-c and VIIIa,b were treated with the reagent XII , under the same as well as more severe conditions. A clear difference in the nucleophilic reactivity of C-3 position between these two classes of isomers is pointed out by the above summarized results.     

1,2-fused pyrimidines. V. Synthesis of 1-alkyl or phenyl-2H-dipyrido-[1,2-a:2′,3′-d]pyrimidine-2,5(1H)-diones

The reaction of 2-[(N-acyl, N-alkyl or phenyl)amino]-4H-pyrido[1,2-a]pyrimidin-4-ones 8a-g with the N,N-dimethylformamide/phosphorus oxychloride Vilsmeier reagent 1 (95°, 90 minutes) afforded 1-alkyl or phenyl-2H-dipyrido[1,2-a:2′,3′-d]pyrimidine-2,5(1H)^?diones, 3-alkyl substituted or not, 10a-g . The starting compounds 8 were prepared by treating 2-amino-4H-pyrido[1,2-a]pyrimidin-4-ones N-alkyl substituted 7a,b or N-phenyl substituted 4 with excess anhydrides (130°, 7 hours) when the 2-(alkylamino) derivatives 7 were used in the reaction, compounds 8 were obtained along with very small amounts of 3-acyl-2-(alkylamino)-4H-pyrido[1,2-a]pyrimidin-4-ones 9 .     

Thiocarbamyolation of amine-containing compounds

Thiocarbamoylation of primary and secondary aliphatic amines with tetramethylthiuram disulfide in various solvents at different temperatures was studied. At 110°C, the reactions with primary amines afforded mixed,N,N-dimethyl-N′-alkyl(cycloalkyl)thioureas and symmetricalN,N′-dialkyl(cycloalkyl)thioureas as the final products, while the reactions with secondary amines gave mixtures of dithiocarbamate salts with “symmetrical” derivatives predominating.     

Synthese und reaktionen von 1-germcyclohexa-2,4-dienen und 1-germacyclohexa-2,4-dien-eisentricarbonylen

1,1-Diakyl(aryl)4-alkyl(aryl)-4-methoxy-1-germacyclohexa-2,5-dienes undergo ether cleavage with sodium in n-pentane or liquid ammonia. Hydrolysis of the resulting sodium salts yields the 1,1-dialkyl(aryl)-4-alkyl(aryl)-1-germacyclohexa-2,4-dienes. Reduction of 1-chloro-4-methoxy-1-germacyclohexa-2,5-dienes with LiAlH₄ can be directed to give the 1H-1-germacyclohexa-2,4-dienes with ether cleavage.The 1H-1-germacyclohexadienes are chlorinated by PCl₅ and brominated by N-bromosuccinimide to the 1-chloro- or 1-bromo-1-germacyclohexa-2,4-dienes, respectively. 1,1-Diethyl-4-phenyl-4-methoxy-1-germacyclohexa-2,5-diene reacts with PCl₃ with ether cleavage and formation of the 6-chloro-1-germacyclohexa-2,4-diene. Ether cleavage is also possible with BCl₃, the 1-phenyl-1-chloro-4R-4-methoxy-1-germacyclohexa-2,5-dienes are transformed into the 1-phenyl-1,6-dichloro-4R-1-germacyclohexa-2,4-dienes.The Fe(CO)₃ complexes of 1,1-dialkyl(aryl)-1-germacyclohexa-2,4-dienes were synthesized.     

Synthesis of 4-N-alkyl and ribose-modified AICAR analogues on solid support

Herein, we report the solid-phase synthesis of several 5-aminoimidazole-4-(N-alkyl)carboxamide-1-ribosides (4-N-alkyl AICARs) and the corresponding 2′,3′-secoriboside derivatives. The method uses the N-1-dinitrophenyl-inosine 5′-bonded to a solid support. This inosine derivative has the C-2 of the purine base strongly activated towards the attack of N-nucleophiles thus allowing the preparation of several N-1 alkylated inosine supports from which a small library of 4-N-alkyl AICAR derivatives has been synthesized. A set of new 4-N-alkyl AICA-2′,3′-secoriboside derivatives have also been obtained in high yields by solid-phase cleavage of the 2′,3′-ribose bond.     

Alkylation des pyrimidines en catalyse par transfert de phase

We report here the first operationally simple and efficient study concerning the phase transfer catalysed alkylation of ambident pyrimidine dianions derived from uracil, thymine, 5-nitrouracil, 5-fluorouracil, 6-chlorouracil, 1,2,3,4-tetrahydro-2,4-dioxoquinazoline, giving selectively the corresponding N₁,N₃-dialkyl derivatives in high yield.     

Syntheses of N-alkyl, N,N-dialkyl, and N-(4-substituted phenyl) O-ethyl thioncarbamates: a kinetic study

Abstract  

The kinetics of the syntheses of N-alkyl, N,N-dialkyl, and N-(4-substituted phenyl) O-ethyl thioncarbamates from sodium ethyl xanthogenacetate, ten alkylamines, and eight substituted anilines were studied at 25, 30, 35, and 40 °C. The reactions were found to follow second-order kinetics. The kinetic (Arrhenius) parameters, such as the activation energy and the frequency factor, as well as the Eyring parameters, such as the standard entropy, the standard Gibbs energy, and the standard enthalpy of activation, were calculated from the second-order rate constants. The mechanism of the reaction was postulated based on the kinetic studies presented and the optimization of the reaction mechanism using the MOPAC PM6 semi-empirical method.     

Tetra-CMPO-derivatives of calix[4]arenes fixed in the 1,3-alternate conformation

Calix[4]arene derivatives fixed in the 1,3-alternate conformation and substituted at one side by four carbamoylmethylphosphine oxide (CMPO) residues were synthesised. Two CMPO groups are directly attached to the wide rim, while the second pair is bound to the narrow rim via a tri- or tetramethylene spacer. Similar compounds, in which two CMPO groups at the wide rim are combined with two picolinamide groups or two ionisable carboxylic groups at the narrow rim, were also prepared. Some of these calixarene derivatives were studied as extractants for lanthanides (La³⁺, Eu³⁺, Yb³⁺) and thorium (Th⁴⁺) from acidic solution into methylene chloride. For selected samples, stability constants in methanol were determined by spectrophotometric titrations. Three compounds (1b′, 13, 17) in the 1,3-alternate conformation and one intermediate in the cone conformation (18) were confirmed by a crystal structure.     

Radical polymerization of N-substituted itaconamic esters and itaconamides

Two kinds of itaconamic esters, α-substituted acrylate derivatives (IAE-I) and α-substituted acrylamide derivatives (IAE-II), as well as itaconamides (IAm) were prepared and polymerized with a radical initiator. It has been revealed that N,N-disubstituted IAE-I as an acrylate is more reactive in polymerization than N,N-disubstituted IAE-II as an acrylamide and that N,N′-dialkyl substituted IAm homopolymerizes but N,N,N′,N′;-tetraalkyl substituted one does not. In radical copolymerization with styrene, IAE-I showed a higher polymerization reactivity than IAE-II. The effects of the N-substituents on the polymerization reactivity were discussed on the basis of conformation of the monomers. The polymers obtained were also characterized. © 1994 John Wiley & Sons, Inc.     

Unexpected formation of 6,7-dihydrobenzo[4′,5′]imidazo-[1′,2′: 1,6]pyrimido[5,4-a]indolizine derivative in the alkylation of 2-amino-1-(benzimidazol-2-yl)-3-(4-methoxybenzoyl)indolizine

An attempt to effect exhaustive alkylation of 2-amino-1-(benzimidazol-2-yl)-3-(4-methoxybenzoyl) indolizine with alkyl iodides in boiling acetone led to the formation of 6,6-dimethyl-8-(4-methoxybenzoyl)-6,7-dihydrobenzo[4′,5′]imidazo[1′,2′: 1,6]pyrimido[5,4-a]indolizine instead of expected N-alkyl derivatives. The product structure was proved by X-ray analysis.     

Efficient method for the synthesis of 1,2,3-triazole functionalized isoxazolidine derivatives by 1,3-dipolar cycloaddition of nitrones with terminal olefins

1-Phenyl-1,2,3-triazole-4-carbaldehyde 1 was treated with different N-alkyl hydroxylamine hydrochlorides 2 using NaHCO₃ to obtain 1,2,3-triazole substituted N-alkyl nitrones 3a–c. The nitrones 3a–c were further reacted with different substituted olefins and furnished 2-alkyl-3-(1-phenyl-1H-1,2,3-triazol-4-yl)-5-(substituted)isoxazolidine derivatives 4a–p in high yields via 1,3-dipolar cycloaddition reaction.     

Cyclisation at very high temperature. Thermal transformations of N-alkyl and N,N-dialkyl cinnamic amides into pyrrolidin-2-ones under FVT conditions

Novel cyclisations of N-alkyl and N,N-dialkyl cinnamic amides to the corresponding pyrrolidin-2-ones under the conditions of flash vacuum thermolysis, are described. It was found that this reaction proceeds at 950-1000 °C affording a mixture of isomeric pyrrolidin-2-ones in various yields. Two possible mechanisms are proposed for the process.     

4,5,6,7-Tetrahydro-1H-imidazo[4,5-c]pyridine-6-carboxylic acids (spinacines)

New derivatives of the naturally occurring amino acid 4,5,6,7-tetrahydro-1H-imidazo[4,5-c]pyridine-6-carboxylic acid (spinacine) are reported. These include amide, ester, 5-alkyl and acyl, and regiospecific N^im-alkyl and aralkyl derivatives. Synthesis via the Pictet-Spengler reaction on N^im-substituted histidines is described. Cyclic hydantoin derivatives of spinacines are included.     

Deep in blue with green chemistry: influence of solvent and chain length on the behaviour of N- and N,N′- alkyl indigo derivatives

Using green chemistry procedures the synthesis of N-alkyl (NC_nInd) and N,N′-dialkyl (N,N′C_nInd) indigo derivatives, with n = 1–3, 6, 8, 12 and 18, was undertaken, leading to compounds with blueish to greenish colors in solution. The effect of the alkyl chain length on the spectral (including color) and photophysical properties of the compounds was explored. This was done with solvents of different viscosities and polarities (dielectric constants). From time-resolved fluorescence and femtosecond-transient absorption (fs-TA) for the NC_nInd derivatives with n = 1 and 2, the decays are, in methylcyclohexane (MCH) and n-dodecane, single-exponential, while in 2-methyltetrahydrofuran (2MeTHF) they are bi-exponential. The excited state proton transfer (ESPT) is ultrafast (<1 ps) for NC_1,2Ind in MCH and n-dodecane, supported by time-dependent density functional theory (TDDFT) calculations, thus showing that both the chain length and solvent influence the ESPT process. For N,N′C_nInd, from time-resolved experiments, and with the exception of the shortest member of the series, N,N′C₁Ind, two conformers are found to be present in the excited state.

Using green chemistry procedures the synthesis of N- and N,N′-alkyl indigo derivatives was undertaken and the effect of the alkyl chain length on the spectral (including color) and photophysical properties of the compounds explored.     

Cyclisation at very high temperature. Thermal transformations of N-alkyl and N, N-dialkyl amides of α,β-unsaturated acids into mono- and bicyclic heterocycles under FVT conditions

Cyclisations of N-alkyl and N,N-dialkyl cinnamic amides to the corresponding pyrrolidin-2-ones under the conditions of flash vacuum thermolysis (FVT), are described. It was found that these reactions proceed at 950-1000 °C affording in various yields the mixtures of isomeric mono and bicyclic γ-lactams, which were separated chromatographically and analysed by means of NMR spectroscopy. Two alternative mechanisms for the title process are proposed.     

The synthesis and characterization of copper(II)–<Emphasis Type="Italic">p</Emphasis>-aminosalicylate complexes with diamine ligands

The complexes were synthesized by the reaction between sodium salt of p-aminosalicylic acid (PAS) and Cu(II) for 1 and corresponding ethylenediamine (en) or its derivatives for 2–6. The complexes were characterized by using elemental analyses, FT-IR, UV–Vis, magnetic moment measurements, and thermal analyses techniques. In complex 1[Cu₂(PA)₄(H₂O)₂], two Cu(II) ions were found as bridged by four μ-O:O′ p-aminosalicylato (PA) ligands, forming a cage structure, and two aqua ligands to form dinuclear square-pyramidal geometry around Cu(II) ions. In the complexes 2–6, the PA (anionic form of p-aminosalicylic acid) coordinated to Cu(II) ions as monodentate manner by using its oxygen atom of deprotonated carboxylic acid and ethylenediamine derivatives coordinated to the Cu(II) ions in bidentate manner to form mononuclear octahedral complexes [Cu(PA)₂(L)₂] (L = ethylendiamine, N,N-dimethylethylendiamine, N,N′-dimethylethylendiamine, N,N,N′,N′-tetramethylethylendiamine, and 1,3-propanediamine, for complexes 2, 3, 4, 5, and 6, respectively). In all the complexes OH and NH₂ groups of PA ligands were not coordinated to metals.     

Interaction of Cucurbit[n = 6∼8]urils and Benzimidazole Derivatives

The structures and optical properties of host–guest complexes produced from cucurbit[n = 6–8]urils and some benzimidazole derivatives have been investigated by ¹H NMR spectroscopy, electronic absorption spectroscopy and fluorescence spectroscopy. The experimental results reveal that calculations of A∼N_Q[n]/N_guest and I_f∼N_Q[n]/N_guest for the same association complex both support a good fit to an identical binding model. In particular, the A∼N_Q[n]/N_guest, I_f∼N_Q[n]/N_guest calculations and the ¹H NMR determinations for three Q[6]–ge(1∼3) complexes and three Q[8]–ge(1∼3) complexes all support a binding model of 1:1 and 1:2 respectively.